Single compartment self-erasing electrochromic devices were apparently first disclosed by Manos in U.S. Pat. No. 3,451,741. However, such devices were not commercially developed until the Byker device of U.S. Pat. No. 5,128,799 was commercialized by Gentex Corporation. Gentex Corporation has reportedly sold over two million of these devices in the form of interior rear view mirrors for automobiles. However, the electrochromically active compounds used in the Gentex device have limited photochemical stability. It would be an advance in this art if single compartment self-erasing liquid filled electrochromic devices could be developed that had better photochemical stability.
Polyoxometalates are known to be electrochromically active. Polyoxometalates are also known to be photochemically active. For example, Currie et al., U.S. Pat. No. 4,612,301 discloses polyoxometalates as photocatalysts for alcohol conversion. Polyoxometalates can even be used for the photooxidation of alkanes, see U.S. Pat. No. 4,839,008 to Hill.